For ADHD, based on a case-control study completed several years ago in a local school district, we have submitted a manuscript on ADHD prevalence among elementary school children. Using our epidemiologic case definition, 15.5% of children in grades 1-5 in this school district had ADHD. Though higher than many estimates, ours is based on systematic screening of all children in the schools and so captures children who may not be evaluated in studies involving clinical diagnoses. Future work will address environmental lead exposure as a possible risk factor for ADHD. (see Z01 ES49034;PI Dale Sandler, EB We have used data from the Agricultural Health study to examine specific pesticides as risk factors for ALS. Organochlorines in general and dieldrin in particular showed evidence of association with ALS although the small number of cases limited precision of estimation. We are planning to examine military and occupational exposures as risk factors for ALS in collaboration with researchers at Duke University and the Durham Veterans Administration Hospital using data from a case-control study of U.S. veterans. (see Z01 ES49005;LI Freya Kamel, EB) We have carried out a case-control study nested within the Agricultural Health Study to examine associations between Parkinson's disease and environmental risk factors, particularly certain pesticide exposures. We are also looking at selected candidate genes as susceptibility factors. This study employs data from the Agricultural Health Study as well as additional questionnaire data and field samples collected expressly for this effort. We have published a finding that rotenone and paraquat increase Parkinson's disease risk. We have also reported that the risk of Parkinson's disease associated with head injury increases dramatically when the subject carries certain alpha-synuclein genetic variants. We have also worked to combine our data with data from other investigators to study risk factors for Parkinson's disease. Two manuscripts have been published: one reporting that genetic variants in the adenosine receptor A2A gene were associated with decreased risk of Parkinson's disease and another reporting that genetic variants in dopamine receptor genes were associated with risk of Parkinson's disease among non-Hispanic whites. Analysis of data is ongoing. (see Z01 ES44007 EB;LI Freya Kamel, EB) Analysis of data from the pilot study of the effects of soy estrogen on neonatal development is complete. We published a manuscript reporting on developmental trajectories through infancy in the size of several putatively estrogen-sensitive organs based on ultrasound imaging. The full-scale study is currently underway at Childrens Hospital of Philadelphia. (see Z01 ES44006 EB;PI Walter Rogan, EB)